Hybrid terrain-adaptive lower-extremity systems

Abstract

Hybrid terrain-adaptive lower-extremity apparatus and methods that perform in a variety of different situations by detecting the terrain that is being traversed, and adapting to the detected terrain. In some embodiments, the ability to control the apparatus for each of these situations builds upon five basic capabilities: (1) determining the activity being performed; (2) dynamically controlling the characteristics of the apparatus based on the activity that is being performed; (3) dynamically driving the apparatus based on the activity that is being performed; (4) determining terrain texture irregularities (e.g., how sticky is the terrain, how slippery is the terrain, is the terrain coarse or smooth, does the terrain have any obstructions, such as rocks) and (5) a mechanical design of the apparatus that can respond to the dynamic control and dynamic drive.

The invention claimed is:  
     
       1. A method for a lower extremity prosthesis or orthosis, the lower extremity prosthesis or orthosis comprising a foot member, a lower leg member, and an ankle joint for connecting the foot member to the lower leg member, the method comprising:
 receiving, from an accelerometer coupled to the lower leg member, an accelerometer signal; 
 receiving, from an inertial measurement unit coupled to the lower leg member, an inertial pose misalignment signal; 
 determining at least one velocity error contribution when the ankle joint is substantially stationary during a walking cycle based in part on the accelerometer signal; and 
 determining at least one velocity error contribution when the ankle joint is substantially stationary during the walking cycle based in part on the inertial pose misalignment signal and a world frame-referenced ankle joint parameter, the world frame-referenced ankle joint parameter to include an indication of at least one of a velocity of the ankle joint or a position of the ankle joint. 
 
     
     
       2. The method of  claim 1 , wherein the inertial pose misalignment signal is a rate gyro signal output by a rate gyro, the method comprising:
 determining the pose of the lower leg member based in part on the accelerometer signal and the rate gyro signal; and 
 determining a corrected pose of the lower leg member using the velocity error contributions. 
 
     
     
       3. The method of  claim 2 , wherein the prosthesis or orthosis comprises a thigh member, the method comprising:
 receiving, from an accelerometer coupled to the thigh member, a second accelerometer signal; 
 receiving, from an inertial measurement unit coupled to the thigh member, a second inertial pose misalignment signal; and 
 determining one or more velocity error contributions based on the second accelerometer signal and the second inertial pose misalignment signal when the ankle joint is substantially stationary during the walking cycle. 
 
     
     
       4. The method of  claim 2 , wherein the prosthesis or orthosis comprises a thigh member, the method comprising:
 receiving, from an accelerometer coupled to the thigh member, a second accelerometer signal; 
 receiving, from an inertial measurement unit coupled to the thigh member, a second inertial pose misalignment signal; and 
 determining one or more velocity error contributions based on the second accelerometer signal and the second inertial pose misalignment signal when a computed position on the foot member is substantially stationary. 
 
     
     
       5. The method of  claim 3 , comprising determining an angle of the lower leg member relative to the thigh member. 
     
     
       6. The method of  claim 1 , wherein the velocity error contributions are determined during a portion of a controlled dorsiflexion state of the walking cycle. 
     
     
       7. A controller for a lower extremity prosthesis or orthosis, the lower extremity prosthesis or orthosis comprising a foot member, a lower leg member, and an ankle joint for connecting the foot member to the lower leg member, the controller comprising:
 logic, at least a portion of which is in hardware, the logic to:
 receive, from an accelerometer coupled to the lower leg member, an accelerometer signal; 
 receive, from an inertial measurement unit coupled to the lower leg member, an inertial pose misalignment signal; 
 determine at least one velocity error contribution when the ankle joint is substantially stationary during a walking cycle based in part on the accelerometer signal; and 
 determine at least one velocity error contribution when the ankle joint is substantially stationary during the walking cycle based in part on the inertial pose misalignment signal and a world frame-referenced ankle joint parameter, the world frame-referenced ankle joint parameter to include an indication of at least one of a velocity of the ankle joint or a position of the ankle joint. 
 
 
     
     
       8. The controller of  claim 7 , wherein the inertial pose misalignment signal is a rate gyro signal output by a rate gyro, the logic to:
 determine the pose of the lower leg member based in part on the accelerometer signal and the rate gyro signal; and 
 determine a corrected pose of the lower leg member using the velocity error contributions. 
 
     
     
       9. The controller of  claim 7 , wherein the velocity error contributions are determined during a portion of a controlled dorsiflexion state of the walking cycle. 
     
     
       10. The controller of  claim 7 , wherein the prosthesis or orthosis comprises a thigh member, the logic to:
 receive, from an accelerometer coupled to the thigh member, a second accelerometer signal; 
 receive, from an inertial measurement unit coupled to the thigh member, a second inertial pose misalignment signal; and 
 determine one or more velocity error contributions based on the second accelerometer signal and the second inertial pose misalignment signal when the ankle joint is substantially stationary during the walking cycle. 
 
     
     
       11. The controller of  claim 10 , the logic to determine an angle of the lower leg member relative to the thigh member. 
     
     
       12. The controller of  claim 10 , the logic to:
 receive, from an accelerometer coupled to a wearer's torso, a third accelerometer signal; 
 receive, from an inertial measurement unit coupled to the wearer's torso, a third inertial pose misalignment signal; and 
 determine one or more velocity error contributions based on the third accelerometer signal and the third inertial pose misalignment signal when the ankle joint is substantially stationary during the walking cycle. 
 
     
     
       13. The controller of  claim 12 , the logic to determine an angle of the thigh member relative to the wearer's torso. 
     
     
       14. The controller of  claim 7 , wherein the prosthesis or orthosis comprises a thigh member, the logic to:
 receive, from an accelerometer coupled to the thigh member, a second accelerometer signal; 
 receive, from an inertial measurement unit coupled to the thigh member, a second inertial pose misalignment signal; and 
 determine one or more velocity error contributions based on the second accelerometer signal and the second inertial pose misalignment signal when a computed position on the foot member is substantially stationary. 
 
     
     
       15. An article comprising a non-transient computer readable medium containing a plurality of instructions that when executed by a processing cause a processor to:
 receive, from an accelerometer coupled to a lower leg member of a lower extremity prosthesis or orthosis, an accelerometer signal; 
 receive, from an inertial measurement unit coupled to the lower leg member, an inertial pose misalignment signal; 
 determine at least one velocity error contribution when the ankle joint is substantially stationary during a walking cycle based in part on the accelerometer signal; and 
 determine at least one velocity error contribution when the ankle joint is substantially stationary during the walking cycle based in part on the inertial pose misalignment signal and a world frame-referenced ankle joint parameter, the world frame-referenced ankle joint parameter to include an indication of at least one of a velocity of an ankle joint coupled to the lower leg member or a position of the ankle joint. 
 
     
     
       16. The article of  claim 15 , wherein the inertial pose misalignment signal is a rate gyro signal output by a rate gyro, the plurality of instructions to further cause the processor to:
 determine the pose of the lower leg member based in part on the accelerometer signal and the rate gyro signal; and 
 determine a corrected pose of the lower leg member using the velocity error contributions. 
 
     
     
       17. The article of  claim 15 , wherein the velocity error contributions are determined during a portion of a controlled dorsiflexion state of the walking cycle. 
     
     
       18. The article of  claim 15 , wherein the prosthesis or orthosis comprises a thigh member, the plurality of instructions to further cause the processor to:
 receive, from an accelerometer coupled to the thigh member, a second accelerometer signal; 
 receive, from an inertial measurement unit coupled to the thigh member, a second inertial pose misalignment signal; and 
 determine one or more velocity error contributions based on the second accelerometer signal and the second inertial pose misalignment signal when the ankle joint is substantially stationary during the walking cycle. 
 
     
     
       19. The article of  claim 15 , wherein the prosthesis or orthosis comprises a thigh member, the plurality of instructions to further cause the processor to:
 receive, from an accelerometer coupled to the thigh member, a second accelerometer signal; 
 receive, from an inertial measurement unit coupled to the thigh member, a second inertial pose misalignment signal; and 
 determine one or more velocity error contributions based on the second accelerometer signal and the second inertial pose misalignment signal when a computed position on the foot member is substantially stationary. 
 
     
     
       20. The article of  claim 19 , the plurality of instructions to further cause the processor to:
 receive, from an accelerometer coupled to a wearer's torso, a third accelerometer signal; 
 receive, from an inertial measurement unit coupled to the wearer's torso, a third inertial pose misalignment signal; and 
 determine one or more velocity error contributions based on the third accelerometer signal and the third inertial pose misalignment signal when the ankle joint is substantially stationary during the walking cycle.